Integrated circuitry fabrication includes deposition of materials and layers over semiconductor wafer substrates. One or more substrates are received within a deposition chamber within which deposition typically occurs. One or more precursors or substances are caused to flow to a substrate, typically as a vapor, to effect deposition of a layer over the substrate. A single substrate is typically positioned or supported for deposition by a susceptor. In the context of this document, a “susceptor” is any device which holds or supports at least one wafer within a chamber or environment for deposition. Deposition may occur by chemical vapor deposition, atomic layer deposition and/or by other means.
FIGS. 1 and 2 diagrammatically depict a prior art susceptor 12, and various issues associated therewith. Susceptor 12 receives a semiconductor wafer substrate 14 (shown in dashed-line view in FIG. 2) for deposition. Substrate 14 is received within a pocket or recess 16 of the susceptor to elevationally and laterally retain substrate 14 in the desired position.
A particular exemplary system is a lamp heated, thermal deposition system having front and back side radiant heating of the substrate and susceptor for attaining and maintaining desired temperature during deposition. FIG. 2 depicts a thermal deposition system having at least two radiant heating sources for each side of susceptor 12. Depicted are front side and back side peripheral radiation emitting sources 18 and 20, respectively, and front side and back side radially inner radiation emitting sources 22 and 24, respectively. Incident radiation from sources 18, 20, 22 and 24 overlaps on the susceptor and substrate, creating overlap areas 25. Such can cause an annular region of the substrate corresponding in position to overlap areas 25 to be hotter than other areas of the substrate not so overlapped. Further, the center and periphery of the substrate can be cooler than even the substrate area which is not overlapped due to less than complete or even exposure to the incident radiation.
The susceptor is typically caused to rotate during deposition, with deposition precursor gas flows occurring across the wafer substrate. An H2 gas curtain (not shown) will typically be provided within the chamber proximate a slit valve (not shown) through which the substrate is moved into and out of the chamber. A preheat ring (not shown) is typically received about the susceptor, and provides another heat source which heats the gas flowing within the deposition chamber to the wafer. In spite of the preheat ring, the regions of the substrate proximate where gas flows to the substrate can be cooler than other regions of the substrate.
Robotic arms (not shown) are typically used to position substrate 14 within recess 16. Such positioning of substrate 14 does not always result in the substrate being positioned entirely within susceptor recess 16. Further, gas flow might dislodge the wafer such that it is received both within and without recess 16. Such can further result in temperature variation across the substrate and, regardless, result in less controlled or uniform deposition over substrate 14.
The sources 18, 20, 22 and 24 can be lamps provided directly over surfaces which are to be exposed to radiation, or can be light directed from lamps which are remote from the surface to which radiation is to be directed. Such aspects of the prior art are shown in FIGS. 3 and 4. Specifically, FIG. 3 diagrammatically shows sources 18 and 22 as lamps provided over a surface of the substrate 14 retained within susceptor 12. The lamps 18 and 22 have surfaces closest to substrate 14 from which emitted light is directed toward substrate 14, and have opposing surfaces from which emitted light is directed away from substrate 14. The surfaces near substrate 14 can be considered forward surfaces, and the opposing surfaces can be considered rearward surfaces. A plurality of reflectors 30 can be provided to reflect light emitted from the rearward surfaces of lamps 18 and 22 toward substrate 14. Emitted light is diagrammatically illustrated in FIG. 3 by arrows 32 (only some of which are labeled), and such arrows show light emitted directly toward substrate 14, and also show light reflecting from reflectors 30 toward substrate 14. Reflectors 30 can have the shown curved shapes, or can be substantially flat.
Referring to FIG. 4, a pair of lamps 18 is shown remote from a surface of substrate 14 (the lamps 22 are not shown in FIG. 4 in order to simplify the drawing, and the lamps 20 and 24 are not shown in either of FIGS. 3 and 4, again to simplify the drawings). A pair of mirrors 34 is shown over substrate 14. Light 32 is directed from lamps 18 toward mirrors 34, and then reflected from the mirrors 34 toward substrate 14.
Various problems can exist with the prior art apparatuses described with reference to FIGS. 1-4. For instance, there can be problems with uneven heating across a substrate, as described above, and there can also be problems with the substrate wobbling or otherwise being improperly aligned within the susceptor. Additionally, there can be problems in obtaining uniform deposition of materials across the substrate, in ascertaining if the deposition across the substrate is uniform, and in ascertaining the approximate thickness of the deposition across the substrate. It is desired to develop improved susceptor apparatus designs and methodologies for utilizing susceptor apparatuses which address one or more of such problems. However, although the invention was motivated from this perspective and in conjunction with the above-described reactor and susceptor designs, the invention is not so limited. Rather, the invention is only limited by the accompanying claims as literally worded, without interpretive or other limiting reference to the specification and drawings, and in accordance with the doctrine of equivalents.